Method for enhancing efficiency of recovery of semi-conductor material in perturbable disproportionation systems



A. REISMAN ET A 3,354,004 METHOD FOR ENHANCING EFFICIENCY OF RECOVERY OF Nov. 21, 1967 SEMI-CONDUCTOR MATERIAL IN PERTURBABLE DISPROPORTIONATION SYSTEMS Filed Nov. 17, 1964 2 Sheets-Sheet 2 0L. M Q n o2 O8 0% Q3 0% Q2 Q2 x: n31; it 6 0 6 0 2 I 2 Jo II 3 H I QN n- 21 2+--T8 o ,L. N 0 n 02 com com 00? com com 02 o o W 0 I N 3 h s ME 2 2 o I. a S M; v M 56 A 2 II. N m. 0 mo 8 1 2 l M V S 3 I #o I W O I 3 q H -QM?" Q lm 21 I--I--H-8 United States Patent METHUD FOR ENHANCING EFFICIENCY OF RECOVERY OF SEMI-CONDUCTOR MATE- RIAL IN PERTURBABLE DISPROPQRTEONA- TION SYSTEMS Arnold Reisrnan and Melvin Berkenblit, Yorktown Heights, and Satenik A. Alyanakyan, New York, N.Y., assignors to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Nov. 17, 1964, Ser. No. 411,881 20 Claims. (Cl. 148-175) This invention relates to a method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems and more particularly to a method for epitaxially depositing germanium in increased amounts by perturbing a mixture of compounds in the vapor phase.

A number of techniques are utilized in the semi-conductor art which teach the vapor transport of a semi-conductor material by a carrier gas from a source to a deposition region to provide for vapor deposition of the semi-conductor material after separation from the carrier vapor. Certain known systems are relatively ineificient and have the further disadvantages that where tetrahalides such as germanium tetrachloride are decomposed at high temperatures in the presence of hydrogen, substrates such as gallium arsenide are attacked. It is obvious,

therefore, that gallium arsenide which is in Wide use could not 'be utilized as a substrate where germanium deposition is desired in high temperature conditions.

Certain other systems characterized as disproportionation reaction systems utilize the variation of equilibrium constants with temperature to produce the deposition of a semi-conductor material from the compounds previously formed at a source region. These systems are known to be relatively inefiicient, the ratio of the semi-conductor material deposited to that transported often being no greater than 25 percent.

It is, therefore, an object of this invention to provide a perturbable disproportionation reaction method having a deposition efiiciency which is greater than prior art systerms.

A further object is to provide a deposition method of increased efiiciency which permits the simplification of system design.

Another object is to provide a deposition method of increased efiiciency in which the recovery of semi-conductor from the vapor phase approaches 89 percent.

Another object is to provide a deposition method of increased efiiciency in which the temperatures at the source and deposition regions are flat.

Still another object is to provide a deposition method of increased efiiciency in which the deposition region temperature is always lower than temperature of source of semi-conductor material.

A feature of this invention is a method for enhancing the efficiency of recovery of a semi-conductor material in perturbable disproportionation systems which utilizes the steps of reacting germanium with a hydrogen, inert gas, halide mixture to produce a mixture of compounds of said elements in the vapor phase, and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, and hydrogen and an inert gas to cause epitaxial deposition of germanium on a substrate.

Another feature is the utilization of the step of perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, hydrogen and helium at a temperature lower than that at which the germanium, inert gas, halide reaction takes place to cause epitaxial deposition of germanium on a substrate.

Another feature is the utilization of the step of perturbing the mixture of compounds by introducing hydrogen into a seed region in amounts equal to the volume of hydrogen and inert gas initially introduced to begin the reaction between germanium, hydrogen and iodine.

Another feature of this invention is the utilization of the step of introducing hydrogen into a seed chamber in amount greatly in excess of the amount of hydrogen and helium initially introduced at a source chamber to enhance the efiiciency of deposition of germanium on a sub strate.

The foregoing and other objects, features and advantages will become more apparent from the following detailed description and accompanying drawings in which:

FIG. 1 is a partial block diagram of a double flow perturbable disproportionation system which is utilized with the method of this invention.

FIG. 2 is a graph showing the efiiciency curves for the system Ge-I -H -I-Ie at an iodine source bed pressure of 4.28 mm. and varying H (H +He) mole fractions.

FIG. 3 is a graphical representation showing efficiency curves for the system Ge-I -H -He at an iodine source bed pressure of 2.15 mm. and varying H /(H -I-He) mole fractions.

In acocrdance with the invention the method taught herein utilizes the perturbabation of a disproportionation reaction in a special way to increase the efliciency of recovery of germanium and includes broadly two independent steps. In the first step, a perturbable mixture is obtained by reacting germanium with a mixture of iodine, helium and hydrogen at a temperature of approximately 600 C. to form compounds of germanium in the vapor phase. At the 600 C. temperature germanium di-iodide (Gel is preferably formed along with hydrogen iodide (HI) in a competing reaction but successful results have been obtained over a temperature range of 550 C. to 900 C. GeI and HI in the vapor phase is then carried to a seed chamber where either hydrogen or a mixture of hydrogen and helium in varying volumes is introduced to perturb the reaction at a 350 C. temperature. The ratio of hydrogen to iodine is effectively increased and the.

partial vapor pressure of iodine is reduced to 1 mm. of mercury where, for instance, it had previously been 2 mm. of mercury. Another competing reaction between the hydrogen and the iodine is also effectively produced. Since the equilibrium conditions for maintaining germanium di-iodide no longer exist at a temperature of 350 C. germanium tetra-iodide and germanium are formed and the germanium in pure form is epitaxially deposited on a substrate at this temperature. Because of the competing reaction between hydrogen and iodine it may be seen that by introducing more hydrogen, that is, in excess amounts, the effective partial vapor pressure of iodine can be reduced causing increasing amounts of germanium to be deposited. In this manner then, the efficiency of epitaxial deposition can be increased up to 89 percent.

Referring now to FIG. 1, there is shown a double flow perturable disproportionation system which is utilized With the method of this invention. Gas sources 1, 2 provide hydrogen and an inert gas, respectively which are delivered to a mixer 3 after passing through high and low pressure regulators 4 and 5, respectively, and flow meters 6. In connection with gas source 2, it should be appreciated that any inert gas such as helium, nitrogen or argon may be utilized without departing from the spirit of this invention. The hydrogen and inert gas mixture from mixer 3 is introduced into a purifier 7 where contaminants are removed. The output mixture from purifier 7 is monitored by flow meter 8 and passes to a hydrogen iodide generator 9 wherein, by reaction between the hydrogen of the mixture and iodine in generator 9, hydrogen iodide is formed providing at the output of generator 9 a hydrogen iodide-helium mixture. Hydrogen and iodine can be introduced directly to a germanium source region, but the hydrogen iodide formed is preferable because equilibrium conditions can be more easily achieved in the Ge source region. The hydrogen iodideinert gas mixture is then introduced into a reaction chamber 10 consisting of a quartz tube 11 which contains a quantity of germanium 12. Germanium 12 is retained in fixed position within tube 11 by quartz wool plugs 13. Quartz tube 11 is shown disposed internally of furnace 14 which may be of appropriate type well known to those skilled in this art. A thermocouple well 15 disposed axially of tube 11 provides access for a thermocouple (not shown) which enables measurement of the temperature of germanium 12. A nozzle section 16 extending from tube 11 carries the reaction products from tube 11 into a dilution-deposition chamber 17 where the reaction products are diluted in a manner to be explained fully carrier gas and that even at low H fractions the efficiency only reaches percent. Thus, under the best possible conditions '75 percent of the Ge picked up at a source is not available for epitaxial growth in a single flow system. The single flow "system has the further disadvantage that a fiat or constant temperature interval at both source and deposition sites is not realized until a H (H +He) fraction of 0.2 is utilized.

The double flow disproportionation system as shown in FIG. 1 increases the efiiciency of drop out of germanium by introducing a diluent gas into dilution-deposition chamber 17 to perturb the mixture by vapor pressure reduction of one of the constituents of the mixture as Well as by a reduction in temperature at the deposition region. Specifically, hydrogen from source 1 and helium from source 2 are mixed in mixer 3 to provide a desired H /(H +He) fraction. After passing through HI generator 9, a hydrogen iodide (HI) plus helium (He) plus hydrogen (H mixture results having a total pressure of one atmosphere. Thus, the sum of the partial pressures will be 760 mm., Hg.

total pHI+pHg +PHe TABLE I.THEOII%%(SIAL EFFICIENCIES IN A HI-HHIe-Ge CONSTANT URE EPIIAXIAL GROWTH SYSTEM [I2 source bed temperature-50 0. I partial vapor pressure at source 2.15 mm.]

hereinafter. Nozzle section 16 is surrounded by a coaxial nozzle section 18 which extends into chamber 17 and carries a diluent gas which is fed from source of hydrogen 19 and inert gas 20 through mixer 21 to a T-junction 22 which is connected to nozzle section 18. Dilution-deposition chamber 17 consists of a quartz-tube 23 sealed about nozzle section 18 at one end thereof and having a removable section 24 at the other end thereof. An exhaust port 25 in section 24 permits the outflow of gases from the chamber 17. Chamber 17 is disposed internally of furnace 26' which is maintained at a lower temperature than furnace 14 in accordance with the teaching of this invention. A quartz boat 27 is disposed internally of chamber 17 and is so positioned that germanium is deposited on substrates placed in the boat when the mixture of compounds resulting from the system reactions is perturbed.

From the foregoing, the distinction between a single flowdisproportionation system and a double flow disproportionation system should be clear. In the former system, the only input to the system would be a hydrogen, iodine, inert gas mixture which would react with germanium to form reaction products from which germanium would be ultimately deposited. In the latter system, the double flow characterization results from the presence of a dilution line consisting of coaxial nozzle section 18 and T-junction 22 which carries a diluent gas from sources 19 and 20.

In the single fiow systems, the reaction products of the reaction between Ge, I, H and an inert gas are perturbed by reducing the temperature to cause deposition of germanium on a substrate, for instance. The resulting deposition is a function of temperature and the efficiency of deposition can be varied by changing the ratio Hg/ (H +He). In a single flow system in which a mixed stream. of HI, He and H is carried over a Ge source at constant total pressure (1 atm.) and in which Ge is subsequently deposited epitaxially, the following theoretical efficiencies are obtainable.

From Table I, it may be seen that the efliciency drops off rapidly with increasing H /(H -i-He) fraction in the with the restriction that the partial pressure of hydrogen be at least equal to the partial pressure of iodine.

The hydrogen iodide, helium, hydrogen mixture is then introduced into reaction chamber 10 where, in passing through quartz tube 11, a reaction between germanium 12 and the hydrogen iodide takes place at a temperature of 600 C. A competing reaction for germanium between hydrogen and iodine occurs resulting in the formation of germanium di-iodide (GeI along with other reaction products. The formation of the diiodide at the 600 C. temperature is a preferred reaction under the equilibrium conditions existing at that tem perature. The reaction products exit from chamber 10 through nozzle section 16 and enter chamber 17 which 15 held at a temperature of 350 C. At this point, Without further action, a temperature controlled disproportionation reaction would take place and germanium would be deposited on substrates in boat 26 and efficiencies of the magnitude shown in Table I would be obtainable. To improve the efiiciency of deposition of germanium, the step of perturbing the equilibrium vapor phase content of germanium in the mixture in chamber 17 by introducing a diluent gas is taken. In a preferred step, the diluent gas takes the form of pure hydrogen introduced from source 19 in volumes greater than the volume of H /(H +He) initially introduced into reaction chamber 10. This step provides the greatest efiiciency improvement. Hydrogen in volumes equal to the volume of the fraction initially introduced provides enhanced efficiencies which, while not as great as those provided by introducing excess amounts of hydrogen, are substantially greater than those obtained in single flow perturbable systems. Further, experiments have shown that efficiency can be increased over that provided by prior art systems by introducing a diluent gas of the same fraction- H /(H +He) as initially introduced into the system.

The mechnism which provides the increased efliciency of germanium deposition depends, under the double flow conditions, both on temperature and on perturbation of the equilibrium vapor phase content of germanium in the mixture. Remembering that germanium di-iodide was preferably formed in reaction chamber by flowing a hydrogen iodide-helium mixture over germanium at approximately 600 C., one would expect to obtain efiiciencies as shown in Table I by simply passing the vapor phase mixture to a lower temperature environment. The introduction of a perturbing gas into dilution-deposition chamber 17 results in an increase in efliciency because the gaseous mixture at the deposition site is rendered over saturated with respect to germanium due to the effective reduction of gas phase iodine content per liter of gas. By introducing a diluent gas into the dilution-deposition chamber 17, the vapor pressure of iodine is reduced, where for instance its vapor pressure was 2 mm. upon introduction into reaction chamber 10, it is reduced to a vapor pressure of 1 mm. in dilution-deposition chamber 17. Under these circumstances, the equilibrium conditions for maintraining germanium and iodine in the di-iodide (GeI form are no longer present and the following reaction causing deposition of germanium takes place at 350 C.

In addition to a germanium dropout due to the temperature decrease, an additional droupout would result due to the supersaturation of germanium which in turn was due to the effective reduction of iodine vapor pressure.

The following Table II shows the effect of dilution by an equal gas volume of hydrogen and helium introduced at the seed chamber. The above efliciencies were obtained using a source pressure of 2.15 mm. of iodine which was effectively reduced to 1.075 mm. of iodine in the deposition region by introducing equal volumes of diluent gas. It can be seen from Table II that the efficiency of dropout of germanium has increased in all cases and that especially at higher H fractions where the system is most controllable reasonable dropouts can be obtained as compared with those of single flow systems. Even more marked effects occur if more than one volume of diluent gas mixture is added.

Finally, dramatic increase in the efficiency of dropout of germanium were obtained by introducing equal volumes of pure hydrogen into chamber 17, instead of an equal volume of hydrogen and helium of the same fraction initially introduced into the system. In addition to the increase in efliciency, the advantage of high hydrogen content systems is obtained at the deposition site since, under conditions of .01 H fraction flow through the germanium source, the effective H fraction at the deposi- 6 manium with an equal flow of pure H introduced at the deposition site.

The efliciency of recovery can be enhanced further by introducing more than one volume of H per volume of H (H -l-He) mixture. At .01 fraction at the source, for example, the efficiency resulting from a 2/1 dilution exceeds 88 percent.

The results disclosed in Tables II and III were ob tained utilizing flow rates of 75 cc./min. Flow rate, however, is not critical as far as efficiency is concerned and it may be varied to increase or decrease the rate of deposition.

It should be appreciated that hydrogen fractions approaching the value 1 at one end of the scale and fractions approaching zero at the other end of the scale and all values in between may be utilized and depositions of germanium with increase efliciency over the single flow regime using the same fraction as a diluent will be achieved.

Referring now to FIGS. 2 and 3, efii-ciency curves for a Ge-l -H -He system at an iodine source bed pressure of 4.28 mm. and 2.15 mm, respectively, and varying H (H -Hie) fractions are shown. In each of the graphs, the abscissa represents temperature in degrees centigrade and the ordinate represents moles of Ge in the vapor phase per mole of I Each of these curves represents the efliciency curves for a single flow disproportionation system wherein the curves of FIG. 3 were determined at an iodine vapor pressure which is one half the iodine vapor pressure used in determining the curves of FIG. 2.

In determining the efficiency of dropout of germanium for a given H /(H +I-Ie) fraction the curves of FIG. 2 and .FIG. 3 can be utilized to show that the efiiciency of deposition of germanium has been enhanced. Referring to FIG. 2, the source temperature is chosen at 600 C. and for a H /(H -i-He) fraction of 0.2, the amount of germanium in the vapor phase per mole of iodine is 0.56 mole. If the system were a single flow system, a deposition temperature of 350 C. for the same 0.2 fraction would show. a value of 0.44 mole Ge/mole I The difference between the two figures (0.560.44)=0.12 is the actual amount of germanium deposited. Since the increase in the efficiency of a double flow system results from an effective reduction in the iodine vapor pressure at a lower temperature, the efficiency curves for a single flow system where the iodine vapor pressure has been reduced can be utilized to show that the deposition of germanium under double flow conditions has been increased. Assuming that the amount of germanium in the tion site becomes an extremely favorable 0.5 when diluted vapor phase per mole of I is the same as shown in FIG.

PRESSURE EPITAXIAL GROWTH SYSTEM [I2 source bed temperature50 0. I2 partial vapor pressure at source 2.15 mm.]

Source Deposition Ha/(Hz-i-He) MgGe picked up Theoretical Temp, or Seed traction at source/mmole dropout of seed Efficiency C. Temp, C. I; MgGe/mmole I:

TABLE III 2 for a 600 C. temperature and a 0.2 fraction, FIG. 3 may be utilized to determine the dropout of germanium at the 350 C. temperature and 0 2 fraction In FIG 3 H (H He H /(H +He) M Ge ick M Ge Recover fjg Dzepqzsition i 1,, dmgpout Emciencg the vapor pressure is half that used for the system of site mn igl a g at FIG. 2. At the 350 C. temperature and 0.2 fraction, the amount of germanium in the vapor phase per mole of I 01 0 5 60 47 79 is 0.38 mole. The amount of germanium deposited is the .03 0.5 53 39 74 difference between the amount of germanium picked up (0.56 mole from FIG. 2) and the amount in the vapor phase at 350 C. (0.38 mole from FIG. 3). Thus, (0.560.38=0.18 mole) is the amount of germanium deposited. The difference in the amount deposited by the 7 system of FIG. 2 and that of FIG. 3 is 0.l8O.12==0.06 mole. From this it may be seen that by diluting to reduce the iodine vapor pressure a fifty percent increase in the amount of germanium deposited can be had and the absolute efficiency of the double flow system is also enhanced.

While it forms no part of the present invention, it should be appreciated that vapor phase doping of germanium can be accomplished using the double flow disproportionation system and epitaxial layers having p or n type conductivity can be deposited.

The method described herein above for enhancing recovery in perturbable disproportionation systems is feasible for all such processes Whether used for epitaxial growth or synthesis so long as the basic reaction is perturbable by a competing reaction.

While the invention has been particularly described with reference to specific examples thereof, it will be understood by those skilled in the art that various changes in procedures may be made therein without departing from the spirit of the invention.

What is claimed is:

1. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, hydrogen and an inert gas to cause epitaxial deposition of germanium on a substrate.

2. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture at a given temperature to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, hydrogen and an inert gas at a temperature lower than said given temperature to cause epitaxial deposition of germanium on a substrate.

3. A. method for enhancing the efficiency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, helium, iodine mixture to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, hydrogen and helium to cause epitaxial deposition of germanium on a substrate.

4. A method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrum vapor phase content of germanium in said mixture by introducing hydrogen to cause epitaxial deposition of germanium on a substrate.

5. A method for enhancing the efficiency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing a mixture of hydrogen and helium to cause epitaxial deposition of germanium on a substrate.

6. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of reacting germanium with a hydrogen, inert gas, halide mixture at a given temperature to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing hydrogen at a temperature lower than said given temperature to cause an epitaxial deposition of germanium on a substrate.

7. A method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture at a given temperature to produce a mixture of compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing hydrogen and helium at a temperature lower than said given temperature to cause an epitaxial deposition of germanium on a substrate.

8. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture, said hydrogen and inert gas being present in a given mole fraction to produce compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing at least one of the perturbing gases selected from the group consisting of hydrogen, hydrogen and an inert gas in a volume equal to the volume of said given mole fraction to cause epitaxial deposition of germanium on a substrate.

9. A method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture, said hydrogen and inert gas being present in a given mole fraction to produce compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing hydrogen in a volume equal to the volume of said given mole fraction to cause epitaxial deposition of germanium on a substrate.

10. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture, said hydrogen and inert gas being present in a given mole fraction to produce compound of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing hydrogen in at least the same volume as the volume of said given mole fraction to cause epitaxial deposition of germanium on a substrate.

11. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

reacting germanium with a hydrogen, inert gas, halide mixture, said hydrogen and inert gas being present in a given mole fraction to produce compounds of said elements in the vapor phase and perturbing the equilibrium vapor phase content of germanium in said mixture by introducing hydrogen in excess of the volume of said given mole fraction to cause epitaxial deposition of germanium on a substrate.

12. A method for enhancing the efficiency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium Within a reaction tube at a given temperature, flowing a gaseous mixture consisting of hydrogen, a halide, and an inert gas over said germanium to react said germanium with said hydrogen and said halide to form a perturbable mixture at said given temperature, introducing said perturbable mixture into a dilution-deposition region of temperature lower than said given temperature and having a seed of semi-conductor material disposed therein, introducing independently into said dilutiondeposition region a gaseous substance adapted to perturb the equilibrium vapor phase content of germanium of said perturbable mixture whereby up to 89 percent of the available germanium in said perturbable mixture is epitaxially deposited on said seed.

13. A method for enhancing the efiiciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium within a reaction tube at a given temperature, flowing a gaseous mixture consisting of hydrogen, iodine and helium over said germanium to react said germanium with said hydrogen and said iodine to form a perturbable mixture at said given temperature, introducing said perturbable mixture into a dilution-deposition region at a temperature lower than said given temperature and having a seed of germanium disposed therein, introducing independently into said dilution-deposition region a mixture of hydrogen and helium adapted to perturb the equilibrium vapor phase content of germanium in said perturbable mixture whereby a portion of the germanium in said perturbable mixture is epitaxially deposited on said seed.

14. A method for enhancing the efficiency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium within a reaction tube at a given temperature, flowing a gaseous mixture consisting of hydrogen, a halide, and an inert gas over said germanium to react said germanium with said hydrogen and said halide to form a perturbable mixture at said given temperature, introducing said perturbable mixture into a dilution-deposition region of temperature lower than said given temperature and having a seed of semi-conductor material disposed therein, introducing hydrogen independently into said dilution-deposition region to perturb the equilibrium vapor phase content of germanium in said perturbable mixture whereby up to 89 percent of the germanium in said perturbable mixture is epitaxially deposited on said seed.

15. A method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium within a reaction tube over a temperature of 550 C. to 900 C., flowing a gaseous mixture consisting of hydrogen, an inert gas, and iodine over said germanium to react said germanium with said hydrogen and said iodine to form a perturbable mixture over said given temperature range, introducing said perturbable mixture into a dilution-deposition region at a temperature of 350 C. and having a seed of semi-conductor material disposed therein, introducing independently into seed region hydrogen and helium to perturb the equilibrium vapor phase content of germanium in said perturbable mixture whereby up to 89 percent of the germanium in said perturbable mixture is epitaxially deposited on said seed.

16. A method for enhancing the efliciency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium Within a reaction tube over a temperature range of 550 C. to 900 C., flowing a gaseous mixture consisting of hydrogen, an inert gas, and iodine over said germanium to react said germanium with said hydrogen and said iodine to form a perturbable mixture over said temperature range, introducing said perturbable mixture into a dilution-deposition region at a temperature of 350 C. and having a seed of semiconductor material disposed therein, introducing independently into said dilution-deposition region hydrogen and helium to perturb the equilibrium vapor phase content of gen manium in said perturbable mixture whereby up to 89 percent of the germanium in said perturbable mix ture is epitaxially deposited on said seed.

17. A method for enhancing the efficiency of recovery of semi-conductor material in perturbable disproportionation systems comprising the steps of:

providing a source of germanium with a reaction tube at a temperature of 600 C., flowing a gaseous mixture consisting of hydrogen, an inert gas, and iodine over said germanium to react said germanium with said hydrogen and said iodine to form a perturbable mixture at said given temperature, introducing said perturbable mixture into a seed region at a temperature of 350 C. and having a seed of semi-conductor material disposed therein, introducing independently into said seed region hydrogen greatly in excess of the amount initially introduced to perturb the equilibrium vapor phase content of germanium in said perturbable mixture whereby up to 89 percent of the germanium in said perturbable mixture is epitaxially deposited on said seed.

18. A method for enhancing the emciency of recovery of semi-conductor material comprising the steps of: introducing a germanium halide compound in the vapor phase which is capable of disproportionating at a deposition site and perturbing the equilibrium vapor phase content of germanium in said compound by introducing hydrogen to cause epitaxial deposition of germanium on a substrate.

19. A method for enhancing the efiiciency of recovery of semi-conductor material comprising the steps of: introducing a germanium halide compound in the vapor phase which is capable of disproportionating at a deposition site and perturbing the equilibrium vapor phase content of germanium in said compound by introducing at least one of the perturbing gases selected from the group consisting of hydrogen and hydrogen and an inert gas to cause epitaxial deposition of germanium on a substrate.

20. A method for enhancing the efiiciency of recovery of semi-conductor material comprising the steps of: introducing a germanium halide compound in the vapor phase which is capable of disproportionating at a deposition site at a given temperature and perturbing the equilibrium vapor phase content of germanium in said compound by introducing at least one of the perturbing gases selected from the group consisting of hydrogen and hydrogen and an inert gas at a temperature lower than said given temperature to cause epitaxial deposition of germanium on a substrate.

References Cited UNITED STATES PATENTS 3,089,788 5/1963 Marinace 148175 3,096,209 7/1963 Ingham 117106 3,152,932 10/1964 Matovich 117200 3,192,083 6/1965 Sirtl 148-174 3,224,912 12/1965 Ruehrwein 148175 DAVID L. RECK, Primary Examiner.

N. F. MARKVA, Assistant Examiner. 

1. A METHOD FOR ENHANCING THE EFFICIENCY OF RECOVERY OF SEMI-CONDUCTOR MATERIAL INPERTURBABLE DISPROPORTINATION SYSTEMS COMPRISING THE STEPS OF: REACTING GERMANIUM WITH A HYDROGEN, INERT GAS, HALIDE MIXTURE TO PRODUCE A MIXTURE OF COMPOUNDS OF SAID ELEMENTS IN THE VAPOR PHASE AND PERTURBING THE EQUILIBRIUM VAPOR PHASE CONTENT OF GERMANIUM IN SAID MIXTURE BY INTRODUCING AT LEAST ONE OF THE PERTURBING GASES SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, HYDROGEN AND AN INERT GAS TO CAUSE EPITAXIAL DEPOSITION OF GERMANIUM ON A SUBSTRATE. 